Clinical surveillance of split renal function in en bloc kidney transplant recipients using ^99mTc-diethylenetriamine-pentaacetic acid (DTPA) dynamic renal scintigraphy: preliminary findings and novel insights

Background: En bloc kidney transplantation (EBKT) involves transplantation of two kidneys, the aorta, and inferior vena cava from a deceased pediatric donor into an adult recipient. Recent articles have shown that EBKT is associated with excellent long-term allograft performance and patient survival. Developmental differences exist between the two transplanted kidneys after EBKT, and it is crucial to assess split renal function. However, there are few studies on the developmental differences between EBKT kidneys. This study aimed to examine kidney developmental differences and evaluate split renal function in EBKT recipients using ^99mTc-diethylenetriamine-pentaacetic acid (DTPA) dynamic renal scintigraphy.

Methods: We conducted a retrospective cross-sectional study of EBKT patients who underwent ^99mTc-DTPA dynamic renal scintigraphy in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from April 2017 to November 2019. Image acquisition from the anterior position and the measurement of kidney depth with the aid of computed tomography were employed. Patients were classified into two groups according to the timing of scintigraphy after EBKT: early (12 months or less) and late (greater than 12 months). For univariate analysis, a t-test was performed to assess transplanted kidney development in different post-transplant periods and the location of the grafts. Reliability analysis was conducted using intraclass correlation coefficient (ICC).

Results: The arcuate renal artery resistive index was significantly lower in medial kidney grafts than that in lateral grafts (0.59±0.05 vs. 0.54±0.07; P=0.010). Gates' glomerular filtration rate (gGFR) was significantly higher in medial grafts (45.34±18.66 vs. 32.29±16.80 mL/min; P=0.004). gGFR was significantly higher in the late group. For the estimated glomerular filtration rate (eGFR) based on serum creatinine (70.69±33.42 mL/min) and gGFR (53.44±19.21 mL/min), ICC was 0.861 (P<0.001).

Conclusions: In EBKT patients, the medial grafts were more developed than the lateral ones. gGFR may reflect changes in split renal function after EBKT. ^99mTc-DTPA dynamic renal scintigraphy monitoring is feasible and effective to assess renal function and complications after EBKT.